It is known to those skilled in the textile field, that the fabric is formed by inserting the weft threads through the shed of the warp threads, the latter being provided with a control-operated reciprocating motion in a direction perpendicular to that of the weft.
Depending on the complexity of the pattern of the fabric to be made, the warp threads may be lifted either in groups, with the heddles system, or one by one with the jacquard system. With the jacquard system, which provides for far superior pattern possibilities, the motion of the lifters which reciprocate the warp threads takes place, at present, in two steps:
The first step is a selection carried out through a pattern formed on punched cardboards joined in a continuous chain, or on a continuous tape of punched paper; PA1 The second step is the motion of the selected lifters which are reciprocted by power members called knives.
This fully mechnical system for the selection and the motion of the warp threads through the lifters has some performance limits and numerous drawbacks owing to the complexity and heterogeneity of the elements it is made up of. Among said drawbacks are a bulky and heavy mechanism which, in order to be operated, has to be mounted above the loom on a suitable and sturdy scaffold; a limited production speed owing both to the remarkable forces of inertia deriving from the reciprocting heavy masses, and to the time needed for carrying out the various selections and movements; a large use of non metal elements: cardboard or paper for the pattern, hemp or nylon ropes for the harnesses, and punched harness boards whith consequent problems arising from changes in size due to environment temperature and humidity; a long and complex preparation of patterns, especially when carried out on cardboards; a limited density of warp threads due to the impossibility of operating under safe conditions with holes too small in diameter and of reduced center distance.
Jacquard devices are known which overcome some of the above mentioned drawbacks and limitations by implementing alternative methods of lifters control with the use of electromagnetic and similar elements, one for every lifter: the electrical pulses to the individual electromagnets being delivered through a direct electronic reading of the pattern to be performed.
However, in these devices, the advantage of eliminating the preparation of the pattern on punched cardboard or paper is undone by the overall dimensions of the electromagnets and the energy consumption thereof.